990) 



Microscopically examined Ihese plagioclases show kernels from labra- 

 dorite to bjtownite, and a repeated alternation of more basic and 

 acidic layers ; besides pale green augite which sometimes occurs as 

 twin crystals according to (100), and hypersthene with a distinct 

 pleochroisni in pale green and pale brownish-yellow colours, we 

 occasionally also remark small ore-crystals among the phenocrists. 

 The glassy base is partly unglassed, and contains edges of plagioclase, 

 small pillars of both augite and hypersthene, and ore-crystals. 



The honioeogeneons inclusions are partly holocrystalline micro- 

 pyi'oxene diorites, partly they only differ from the surrounding rocks by 

 the strong increase of the crystals of plagioclase, augite, hypersthene 

 and ore in the groundmass, whereas the glass only occurs caught 

 between the crystalline constituents ; they apparently have formed 

 crystalline parts in the rising magma, their total crystallisation occur- 

 ring simultaneously with that of the surrounding lavas. The micro- 

 dioi-ites are partly rather abundant of ore and then appertain to a 

 cleavage product more basic than the surrounding lavas. Exception- 

 ally olivine, in a small quantiry, was found among the constituents 

 of these inclusions while it is wholly absent in the examined samples 

 of the surrounding pyi-oxene andesites. The occurrence of olivine in- 

 dicates cleavage products of the common mothermagma in which this 

 mineral may crystallize, these cleavage products being known to us 

 from the olivine-containing pyroxene andesites and basalts of volca- 

 noes of the same complex^). (Merapi, Raoeng, Gd. Pondok, Koekoesan). 



Goentoer. 



During the ascension of the Goentoer in April 1913 a scattered 

 vegetation turned out to have reached the very top, whereas Verbeek, 

 on the smooth cone that has but few incisions even now, did not 

 meet with a single trace of vegetation above the limit af 1000 m. 

 The rocks of the Goentoer complex, as far as they have been examined 

 by LoRiÉ, Behrens, Verbeek, and myself, are chiefly basalts, that 

 sometimes graduate into olivine-containing andesites, andesites without 

 olivine also occurring. The products of the youngest point of eruption 

 (the Goentoer properly speaking) which now only at the northwestern 

 side shows some vapor of water and SO, rising from it, but which 

 during the preceding century was frequently very active, consist of 

 streams of lavas and gravel, or big blocks of often very porous rocks, 

 which entirely cover the upper part of the streams of lava. As far 

 as they have been examined, they are all found to be olivine basalts, 



1) K. D. M. Verbeek and Fennema, loc. cit. 



